Improve documentation concerning disk IO

docs/aoa/disk.rst

@@ -8,6 +8,11 @@ Disk I/O
 Glances displays the disk I/O throughput. The unit is adapted
 dynamically.
 
+You can display:
+
+- bytes per second (default behavor / Bytes/s, KBytes/s, MBytes/s, etc)
+- requests per second (using --diskio-iops option or *B* hotkey)
+
 There is no alert on this information.
 
 It's possible to define:

docs/man/glances.1

 .\" Man page generated from reStructuredText.
 .
-.TH "GLANCES" "1" "Jul 28, 2018" "3.0.rc5" "Glances"
+.TH "GLANCES" "1" "Aug 05, 2018" "3.0.rc5" "Glances"
 .SH NAME
 glances \- An eye on your system
 .